The present invention relates to a method for incorporating a carrier element in a card body and to a semifinished product in the form of a card body.
In the production of identity cards that are used as personal I.D., credit cards, debit cards or the like, the carrier element is connected with the card body for example in a recess provided in the card for taking up a module or carrier element. One possibility, for example, is to connect a carrier element or a module with the card body permanently with the aid of an adhesive layer.
Known methods for incorporating a carrier element or module in a card body chiefly use hot-sealing adhesives or contact adhesives. Unlike contact adhesive, hot-sealing adhesive must be thermally activated, i.e. the components can only bond under the action of heat. The necessary heat can be supplied to the hot-sealing adhesive for example via suitable heat dies. Contact adhesive offers the advantage over hot-sealing adhesive that a good and permanent bond can be had without the action of heat. However, since contact adhesive is already adhesive at normal temperature it is more difficult to handle during the method steps; for example contact adhesive can stick to the machine parts in undesirable fashion.
The modules or carrier elements, that are preferably stamped out of an endless film, generally comprise a substrate on which one or more integrated circuits are connected with strip conductors. The strip conductors lead to contact surfaces located on the substrate that permit communication with corresponding devices. The IC module and the strip conductors leading from the IC module to the contact surfaces can be surrounded by a casting compound as protection from mechanical loads.
A representative example of the many known methods for incorporating a carrier element or module in a card body is the method known from EP-A 0 201 952. In this method a carrier element or module is connected with the card body in a recess in the card with the aid of a contact adhesive disposed on the carrier element. The method steps are as follows. Circular openings are stamped in a contact adhesive tape comprising a double-sided contact adhesive film that is covered on each side by a protective film. The contact adhesive tape provided with the openings is brought together with a carrier film on which the integrated circuits are mounted, and connected therewith after a first protective film is removed. The carrier film is sprayed with a protective layer, whereby the contact adhesive film covered by a second protective film forms a mask that covers the areas not to be sprayed. Before the carrier elements are stamped out with the corresponding contact adhesive rings the second protective film is removed. In an additional working step the contact adhesive film connected with the carrier film is brought together and connected with a third protective film. The contact adhesive film is thereby covered by the third protective film in such a way that the contact adhesive rings provided for connecting the carrier elements with the card bodies are not covered when the carrier elements are stamped out. The third protective film prevents the contact adhesive film from sticking to the card body or to the die-plate of the stamping die when the carrier elements are stamped out.
The method has the disadvantage that very precise positioning is required to bring together or connect the additionally used third protective film with the contact adhesive film so that the adhesive surfaces of the contact adhesive rings are not covered by the protective film. Furthermore, the known method has the disadvantage that the additionally applied third protective film creates a distance between the punch and the die-plate when the carrier elements are stamped out, so that fuzzy edges are obtained in the stamping operation. This can lead for example to fuzzy stamping contours.
The invention is based on the problem of facilitating the incorporation of a carrier element in a card body while simultaneously obtaining a good and permanent bond between the carrier element and the card body.